A “valve” is a functional unit with moveable switches, and used to control the flowing, pausing, flow quantity and pressure of fluid in pipelines. Its functions break into five parts: (1) a front-and a back part (2) an adjustment of the flow quantity (3) prevention of the countercurrent flow (4) the alteration of the flow direction and (5) pressure-control of fluid.
For life-related tap water, gases in semiconductor plants and chemicals, food or products of petrifaction plants, valves are needed to adjust the flow quantity of a fluid, to control the flow rate and pressure or to control its fluid-acceptance as long as the fluid is conveyed by pipelines. Thus, we see that the valve is an indispensable part in the semiconductor industry, chemical industry and food industry.
The internal surface of pipes, used to transport fluid bodies, mostly goes through lapped finishing or electrolytic polishing for high cleanness and anticorrosion. Advanced integrated circuits, LCD, III-V industry and so on have stricter standards on the cleanness, anticorrosion and gas leakage rate.
To reduce the leakage rate of fluid bodies in pipes, many types of valves are developed to control the on and off state of fluid bodies, for instance:    1. The American U.S. Pat. No. 5,730,423 reveals a metal diaphragm valve, wherein an annular sealing base is set on the inlet of a valve chamber. The diaphragm is made of springy metal and dish-shaped. When not pressed, the diaphragm does not touch the sealing base; while pressed, it shall be deformed to contact the sealing base for sealing. The diaphragm directly contacting the annular sealing base is made of hard steel, while the diaphragm next to it is made of soft metal. This diaphragm valve is designed to achieve driving fit by pressing metal surfaces together, but dust particles are easily generated, due to metal frictions, thus it fails to meet the requirements of super cleanness.    2. The American U.S. Pat. No. 6,092,550 reveals a diaphragm valve, which controls the inflow and outflow of fluid bodies by using the driving fit between diaphragms and a non-metal axle ring, instead of a metal one. First, put a metal axle ring on the inlet of air in-flow channel, then set a non-metal axle ring around the above-mentioned metal one. Below the non-metal axle ring, the metal axle ring is deformed by a clamp device and fit with the non-metal axle ring by way of rivet connection. The negative part of this is, that the metal axle ring and non-metal axle ring are not maintainable or replaceable, and the fitting of them is likely to cause surface scuffing and to damage their anticorrosion and cleanness.    3. American U.S. Pat. No. 5,485,984 reveals a diaphragm valve, which adopts a removable sealing metal ring that contains an input channel and an output channel of fluid bodies. The part contacting with machines is made of synthetic resin for sealing. This diaphragm valve is easy to install and maintain; yet there are difficulties in tolerance matching and slipping positioning in case of production and assembly, for the sealing structure of the valve body is a removable metal ring, and it is not suitable for production in large quantities.